Portable electric saw



M. W. BARDWELL PORTABLE ELECTRIC sAw Feb 16, 1932 Filed June 20, 1929 2Sheets-Sheet 1 llll ill.

|| ll l l mlliltlll Feb. 16, 1932. M. w. BARDWELL 1,845,644

PORTABLE ELECTRIC SAW Filed June 20, 1929 2 Sheets-Sheet 2 Patented Feb.16, 1932 UNITED. STATES MARTIN w. BALRDWELL, or BELGHERTOWN,amssaonusnrrs PORTABLE ELECTRIC saw Application filed June 20,

My invention relates to electrically driven power devices, and forpurposes of, explanation and description I have shown the same asexemplified in a portable saw structure.

The general object of the invention is to provide a device of simpleconstruction which is compact and is capable of utilizing with greateiiiciency the energy generated by the power device employed foractuating the 0 operating mechanism thereof.

It is a further object of the invention to provide means whereby arelatively long stroke of a tool or other object may be attained by theoperation of mechanism which 5 is adapted to be located in a relativelysmall space.

A still further object of the invention is to provide means interposedbetween the driving and the driven elements whereby the wearing effectupon the driving element by the contact of the driven element therewithis reduced to a minimum.

To the foregoing and other ends the invention comprehends theconstruction and arrangement of parts as hereinafter described n CI indetail, particularly pointed out in the claims, and as illustrated inthe accompany ing drawings wherein I have illustrated the invention inthe form which is at present pre- (5 ferred by me. However, it should beunderstood that the invention is susceptible of embodiment in otherforms of construction than that shown and that mechanism within the m,inventionmay be employed for the actuation Fig. 2 is a similar view of afragmentary portion of the structure with the parts enlarged and withcertain parts, not shown in Fig. 1, being indicated in dash lines andwith a portion broken away and sectioned to show a detail ofconstruction;

1929. Serial No. 372,507.

Fig. 3 is a transverse sectional view taken along the line 3-3 of Fig. 1

Fig. 4 is a sectional view taken along the line 44 of Fig. 1; and

Fig. 5 is a transverse sectional view taken on the line 5 5 of Fig. 1.

In the drawings I have shown a casing 1 of rectangular shape one side ofwhich is open and is adapted to be closed by means of a cover plate 2secured in place by means of fastening rods 3 which extend through thecasing near the top and bottom edges thereof, as indicated in thedrawings. The casing may be of solid box-like formation, as shown, ormay consist of any other formation of a character to support. theoperating mechanism of the structure which will be herein after setforth in detail. The casing is provided upon oneof its sides near itsrear end with an integral tubular projection 4 having a lateral flange 5to which a motor 6 of any known suitable construction is attached; Themotor is provided withthe usual motor shaft, indicated at 7, and isconnected by means of reduction gearing, indicated as a whole at 8, witha worm shaft 9 supported in antifrictional thrust bearings 10 and 11provided upon the casing 1 inside of and in adjoining relation to itsrear end. The casing is provided with a bracket 12 upon which may bemounted any suitable form of switch 13 for opening and closing thecircuit 14 through the motor 6 for operating the latter. A spring, asindicated at 15, or any other suit able means may be employed fornormally holding the switch in open position, and the closing of thesaid switch may be effected in opposition to the action of thesaidspring by a finger or hand-piece 16. A worm 20 is supported uponandkeyed to an enlarged por tion 20 of the shaft 9, as shown in Fig. 2,and is in engagement with a gear 21 which is. mounted upon a cylindricalbushing 22 which in turn is supported upon a pin 23 which projectsoutwardly from the bottom of the casing 1 toward the cover 2 whichcloses the open sidethereof. The bushing 22 not only fits in the openingthrough the gear 21 but also projects into and practically through asimilar opening 24 in agear 25. The bush ing is provided with elongatedprojections constituting gibs 30, which gibs are in engagement withgrooves or slots 31 and 32 provided in the openings through the gears 21and through which the bushing 22 extends. The gear 25 is in mesh with agear mounted upon the intermediate portion of a pin 36 supportedinparallel relation to the pin 23. The bushing 22 with the gears 21 and 25thereon is rotatable upon the pin 23 wh-i-lethe gear 35 is rotatableupon the pin 36. The pins 23 and 36 are retained in openings 37 providedin the bottom of the casing 1 by means of binding screws 40.

The shaft 9 is held against axial movement by collars 40 one side ofeach of which engages the shoulders formed by the enlarged porti0n20 ofthe shaft and the opposite ends of the worm 20, and the opposite orouter sides of which are seated against the bear ings 10 and 11.

For the purpose of providing a supplemental bracing and steadyingsupport for the upper ends of the pins 23 and 36 I have provided-amemberof T-shape having a portion 41 which extends between the opposite sidesthe top and bottom sides) of the casing 1 and secured thereto by meansof connecting screws 42, and also having a portion 43 which extends atright angles to the portion 41 and is connected at its outer end bymeans of connecting screws 44 to the adjoining end of the casing 1.Theupper end portions of the gear supportingpins 23 and 36 are reduced,as indicated at 50, and the said end portions pro- .ject into openings51 in the underneath side of the portion 41 previously referred to. Itwillbe obvious that'the pins 23 and 36 are supported at their oppositeends, thereby greatly increasing their capacity for withstanding andresisting forces which may be applied laterally thereto. For the purposeof actuating a saw 52 or other object I have provided a supporting rod53 or'the like, having'means such, for example, as that shown at 54 forsupporting the said saw or other tool. The supporting member 53 isguided at its outer end in 'a split bearing 55 removably mounted in anopening which is provided in the outer end wall of the casing 1. Theinner end of the supporting rod or bar 53 termi nates in a 'T-head orenlargement having a notch in-its outer side or edge into whichextendthe overlapping outer ends of links 56 which are held in placewithin said notch 'by'a pivot'bolt or pin 57. The links 56 constituteparts of a lazy tong structure, indicated as a whole at 59. The outerends and the intermediate portions of the links constituting-the saidstructure are pivotally connected together in the usual manner. For thepurpose of causing the expanding and contracting movements of the lazytong structure .59 .to take place in a substantially single plane, or inother Words, to prevent lateral vibration thereof, I have connected thesame to guide blocks 60 and 61 the opposite or upper and lower edges ofwhich are supported in grooves 62 provided upon the inner edges of guidebars 63 which are supported upon the inner side of the bottom of thecasing 1, being connected thereto by means of screws 64. The guide block60 and the terminal T-head of the supporting member 53 are formedintegrally so that the said block and supporting member constitute asingle integral structure possessing a high degree ofrigidity; One ofthe pivots 65 by which the middle portions of the links of the lazy tongstructure are connected together extends into and is supported upon theguide "block 61. By this means the lazy tong structure is supported atits inner and outer ends, whereby its in-and-out movements (causedlbymeans hereinafter to be described) are effected in straight lines; inother Words, lateral vibration of the actuating link structure isprevented. Of course the connecting rod or bar 53 is further guided bymeans of the bearing 55 through which it operates.

For the purpose of causing pivotal movements of'the links of the lazytong structure with respect to each other and thereby causing in-and-outrectilinear movement thereof I have provided the innermost links and 71of the said structure with enlarged rear end portions which are providedwith openings 72 and 73 therethrough, within which openings are locateddisks 74-and 75 which are mounted upon and eccentrically of the gears 25and 35.

The centers of these disks are connected to the gears 25 and 35 by meansof pins 76 and 77 located eccentrically of the said gears respectively.The said disks 74 and 75 are provided respectively with openings 80 and81 located. eccentrically thereof through which the pins or posts 23 and36 project. By the engagement of the disks 74 and 75 with both the pins76 and 77 and 23 and 36 it will be apparent that the forces transmittedthrough the said disks are resisted by both pins, thereby preventing aconcentration of forces upon the pins 76 and 77 which mightresult'in'the breaking thereof. If preferred, the disks 74 i and 75 maybe formed integrally with the gears 25 and The disks 74 and 75 arelocated between the gears 25 and 35 and the ends of projections 82provided upon the inner side of the portion 41 which constitutes asupplemental supporting means for the pins 23 and 36.

By reducing the diameters of portions, as

indicated at 50., of the pins or posts .23 and 36 I also am enabled toreduce the sizes or of the drawings. During the rotation-of the 1 gears25 and 35 and of the disks Hand mounted thereon it will be apparent thatwhen in certain positions the outer edge portions of the disks willoverlap each other. For example, if the said disks and gears be rotatedthrough 180 from the positions in which they are shown in Fig. 1 of thedrawings, it will be apparent that at such time the edge portions of thedisks 7 4c and 7 5 will overlap each other. To permit such overlappingin the construction as shown in the drawing a lower portion of the disk7 42 is cut away, as indicated at 82, and likewise a portion asindicated at 82 of the outer end of the link 7 0 is cut away. Thesecut-out or cut-away portions are located in proper positions to permitthe edge portion of the disk 7 5 to project thereinto as the said disks7 4 and 75 move into overlapping relation with respect to each other.

In the operation of the device the worm 20 is rotated toward the right,thereby causing the gear 21 and the connected gear 25 to rotate in ananti-clockwise direction, as indicated by the arrows 83 shown in Fig. 2of the drawings. The gear 25 is in mesh with the gear 35, so thatrotation of the latter in a clockwise direction (as indicated by thearrow 84 in Fig. 2 of the drawings) is effected.

As illustrated in Figs. 1 and 2, the pins 76 and 77 and the disks 74-and 7 5 are located in positions the farthest apart of any occupied bythem during the operation of the device. Movement of the gears 25 and 35from the positions shown in Figs. 1 and 2 in the directions of thearrows 83 and 84 causes a movement of the pins 7 6 and 77 toward theright along circular paths and toward each other, the disks 74 and 75being thereby caused to revolve about the reduced portions 50 of thepins 23 and 3 6. The pins 7 6 and 77 moving in the directions justindicated act through the disks 74 and 7 5 to cause pivotal movement ofthe links of the lazy tong structure and to effect rectilinear outwardmovement of the latter as a whole to cause outward movement of the sawor other device having connection therewith and which is to be actuatedthereby. This cutward movement, which begins at a moment just before thepins 76 and 77 arrive at the points shown in the drawings, is begunslowly and then speeds up, the movement slowing down as the lazy tongstructure approaches the end of its outward movement. When the pins 76and 77 and the disks 74 and 75 have reached certain points in theirmovements the lazy tong structure as a whole begins a movement in thereverse or opposite direction. This movement likewise is at first slowand then speeds up, and finally slows down as the lazy tong structure asa whole approaches the limit or end of its reverse movement. Thus areciprocating rectilinear movement of the lazy tong structure as a wholeis effected whichy maylbe utilizedinthe actuation of a saw or of anyother device for which it may. be adapted.

,Thepivotal movement of the links 70 and 71 and the correspondingmovementsofv the remaining links of the lazy tong structure to drive thetool 52 or other device to effect the work desired to be performedthereby results .in the imposition of stresses and forces upon the gears21, 251 and 35 and upon the worm 20. As a result of the stresses andforces thus applied between the engaging driving and driven gearstheremay be considerable. wear of the contacting surfaces, particularlythe. surfaces of the driving face of, the wor1n20. I have discoveredthat by the employment of a bushing- 22 for-connecting the two gears21and 25 the wear of the engaging surfaces of the gear teeth of the gear21 and of the worm 20 is greatly reduced. Particularly is this true ofthe driving surface ofthe worm 20. This is true notwithstanding the factthat the-bushing 22 has rigid connection with the said gears 21 and 25,the fit between the said bushing and-the the means employed thegears 35and 25.1nust be driven in directions related to each other asillustrated in the accompanying drawings, in order that the lazy tongstructure may be actuated for elfectingreciproeatory movement of the rodor bar 53 by means of which the Work to be effectedmay be performed.

It may be noted that for the purpose of facilitating and rendering moreconvenient the handling of the device I have so related the parts of thestructure that the center of gravity is located at some point within themotor 6 or at some point directly and immediately above the said motor,so that when the device is supported by means of a suspending means thecasing will occupy a horizontal position, with the motor 6 dependingtherefrom. To further facilitate the transportation of the device I haveprovided the casing with a handle 85 which is located preferablydirectly above the motor 6.

It will be seen that by my invention I have provided a device of thecharacter indicated which is simple, compact, strong, and durable, andwhich may be employed for various purposes. One of the uses for whichthe inventionis adapted when embodied in a portable saw structure, suchas is exemplified in the acine zcompa'nying drawings, is that of sawingor cutting limbs tro-m trees. The device being light :may be hoistedreadily upwardly into proper relation to thelimb of a tree which it isdesired to remove.

Having thus described my invention, what lclaim and'desireto' secure byLettersPatent is:

1. A power driven saw comprising a casing, :a motor supported thereon, aworm shaft mountedwithinthe casing and driven by the motor, a worm wheelgeared to the worm shaft, "a gear wheel yieldingly secured to the wormwheel, a second gear wheel meshing therewith, an eccentric on each ofsaid gear wheels, a 'lazy tong device supported within said casing andhaving the terminal links on one end thereof in the form of eccentricstraps, one of which is in operative engagement with each of saideccentrics, a connecting rod attached to'the opposite end of said lazytong device and extending to 'the exterior of said casing, and a sawsecured to said connecting r0 1 2. In a power driven tool thecombination of a casing, a motor supported thereon, a worm shaft.carried'by the casing and driven by the motor, a worm wheel geared tothe worm shaft, .a gear wheel yieldingly secured tothe worm wheel, asecond gear wheel meshing therewith, an eccentric on each of said gearwheels, a lazy tong device within said casing and having the terminal"links on one 35 end in the form xof eccentric straps one of which is inoperative engagement witheach of saideocen'trics,guide blocks secured tosaid lazy tong device, a guideway for said guide blocks von said casing,and a connecting rod 40 attached to the opposite endof said lazy tongdevice and projecting from said casing.

In testimony that I claim the foregoing as my invention I .havehereuntosigned my name thisl lthday of June, A. D. 1929.

MARTIN W. BARDWELL.

